Oriental x Asiatic lily hybrids, often referred to as OA lilies, are a type of hybrid lilies that result from crossing two distinct lily species: Lilium auratum (oriental lilies) and Lilium species in the asiatic lilies’ botanical division. These hybrids combine the desirable traits of both parent species, creating lilies with unique and striking characteristics.

In the last few years, advancements in technology and scientific endeavors have led to remarkable achievements in creating new interspecific hybrids, called interdivisional hybrids. These achievements have been made possible through innovative techniques and sophisticated methods of pollination. For instance, the OT hybrids (Orienpet) involve crossing oriental lilies with trumpet/Aurelian lilies. OT hybrids can be outstandingly beautiful, robust and durable and I adore them. In fact, I cannot have enough of them!! However, I only discovered OA hybrids this summer after planting them last year.

Where do OA lilies come from?

Oriental lilies are known for their large, fragrant, and showy flowers with a wide range of colors, including white, pink, red, and various bicolor variations. They are also famous for their intense fragrance, making them popular choices for cut flower arrangements and gardens. Oriental lilies are hybrids of Lilium auratum, also known as the golden-rayed lily, a species of lily native to Japan.

Asiatic lilies, on the other hand, have a broader spectrum of colors, including vibrant oranges, yellows, pinks, and reds, but they generally lack the strong fragrance of oriental lilies. They are often early bloomers and are prized for their hardiness and ability to thrive in various garden conditions. Asiatic lilies are the results from the crossing and hybridization of various lily species within the section Sinomartagon of the genus Lilium. Asiatic lilies are valued for their early bloom time, hardiness, and adaptability to different garden conditions, making them popular choices among gardeners and florists alike.

By crossing individuals from these two lilies’ divisions, horticulturists and breeders aim to combine the best attributes of each type, a similar process than the one with the other interdivisional hybrids Orienpet (oriental x trumpet).

The resulting oriental x asiatic hybrids (OA) can exhibit a wide array of characteristics, including various flower colors, and bloom times, combining the compact height and upward-facing flowers of an asiatic lily with the large flowers of an oriental lily. However, they are only slightly fragrant, though not as much as their oriental parent. They grow to a height of 90 to 100 cm. They bloom from mid to late summer. These hybrids may also be more disease-resistant and adaptable to different growing conditions compared to their parent species.

OA cultivars

New hybrids and cultivars have been developed in the last few years. Both the Royal Horticultural Society and the North American Lily Society list them in Division VIII : Other hybrids of their classification. Some growers, mainly from the Netherlands, may describe them as AOA if they are advanced crosses Asiatic x Oriental x Asiatic.

If you are a gardener like me, peruse on the shelves of bulbs in local nurseries. Online resources are also a very good sources for plants to buy. At the moment, I have two cultivars of OA, both only registered in 2017 by the Lily Company B.V. in the Netherlands as AOA:

‘Hotel California’ is a great AOA hybrid that bloomed for the first time this year in my garden. The flower shape and size (more than 8 inches across) is typical of an oriental lily and the yellow-red color scheme from an asiatic lily. The tepals, including the throat, are ruffled and mainly vivid yellow with numerous red spots.

‘Avalon Sunset’ is another great AOA I have tentatively identified from a bag of OT mix bought at Costco. It definitely has the flower shape and size of an oriental lily and the color scheme from an asiatic lily in red, orange and yellow. The tepals are predominantly moderate reddish orange over brilliant greenish yellow margin. The throat is greenish yellow along and beside nectary ridges. It is very similar to ‘Kaveri’ which I have also seen available in catalogs.

How to plant and grow OA

OA hybrid lilies must be planted deep, in fertile, humus-rich, well-drained soil. The top of the bulbs must be covered with a minimum of 2 inches of soil. In fact, 3 to 5 inches is not too deep during high temperatures of late spring and early summer. A 4-inch x 4-inch spacing is commonly recommended. However, some growers of hybrid lilies for cut flowers use closer spacings. Water the bulbs in well after planting.

Note that bulbs require a cold period of at least 8 weeks, ideally at maximal temperatures between 32°F and 34°F, before planting. Bulbs purchased in the spring have likely undergone winterization and will be ready to bloom in the following weeks, albeit on shorter stems. Additionally, some flowers may only appear the next year.

Water as needed to keep soil evenly moist, especially in hot weather. Remove faded flowers for best display. They may also be damaged by the lily beetles, so constant monitoring during the growing season is recommended.

As the North American Lily Society states on its website, the development of newer lines by crossing asiatic and oriental lilies will bring novel hybrids promising to bring a wealth of diversity, exquisite beauty, improved health, resilience, and increased disease resistance. The future holds great potential for even more stunning and robust lily varieties worth considering if you are planning to plant lily bulbs in your garden.